This invention relates to high-friction, cured silicone compositions, methods for their manufacture, and methods for their use, including articles formed therefrom having a gripping surface.
Hand-held articles desirably have a surface that can be securely gripped to prevent slipping or dropping of the article under a variety of conditions such as wet, dry, or in the presence of particulates such as sand, dirt, or lubricating powder. Making the surface soft can enhance grip, and is preferred for lightweight plastic components, but it can also adversely affect the durability of the gripping surface. It has heretofore been difficult to achieve a balance between the properties required for enhanced grip, for example softness and high coefficient of friction, and the mechanical properties required for durability.
Thick silicone sheets having a thickness of greater than 2.5 mm and sufficient softness (e.g., Shore A Durometer of less than about 60) can provide a suitable surface for gripping and sufficient durability. However, when the silicone in the form of a thin sheet (less than or equal to 2.5 mm thickness) it is more prone to tearing. A reinforcing backing can be used to reinforce the layer, but to be effective the adhesion of the silicone layer to the backing layer must be sufficient to prevent separation. This can be difficult to achieve under conditions of repeated stress. An adhesive can be used between the silicone layer and the backing, but effective adhesives can degrade the silicone over time. Moreover, silicone adhesives are expensive and non-silicone adhesives do not stick effectively to thin silicone elastomers.
Accordingly, there remains a need in the art for a gripping surface comprising a cured silicone having a durometer and a coefficient of friction effective to provide a good gripping surface, as well as enhanced adhesion to a variety of substrates, optionally with the use of an adhesive for adhesion to articles benefiting from improved grip. It would be a further advantage if the cured silicone could be durable when used at thickness of less than or equal to 2.5 mm.